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Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.

ABSTRACT: BACKGROUND:We previously found a significant benefit of vitamin C supplementation in asthmatic children. PURPOSE:To test whether the effect of vitamin C on asthma is heterogeneous over the participant population. METHODS:Egyptian asthmatic children between 7 and 10 years of age (n = 60) were included in the cross-over trial. They were administered 0.2 grams per day of vitamin C and placebo for separate 6-week periods. The variation in the vitamin C effect on two clinically relevant outcomes was analyzed: the childhood asthma control test (C-ACT), which measures the severity of asthma symptoms (the scale ranges from 0 to 27 points, < 20 points indicating unsatisfactory asthma control), and FEV1. We used linear modeling to examine the variation of the vitamin C effect in the subgroups. RESULTS:The effect of vitamin C on the C-ACT was significantly modified by age and baseline C-ACT levels. In the children aged 7.0-8.2 years with a baseline C-ACT of 18 to 19 points, vitamin C increased the C-ACT score by 4.2 points (95% CI: 3.3-5.3); whereas in the children aged 8.3-10 years who had a baseline C-ACT of 14 to 15 points, vitamin C increased the C-ACT score by only 1.3 points (95% CI: 0.1-2.5). The effect of vitamin C on the FEV1 levels was significantly modified by age and exposure to dampness. In the children aged 7.0-8.2 years with no exposure to dampness, vitamin C increased the FEV1 level by 37% (95% CI: 34-40%), whereas in the children aged 8.3-10 years with exposure to dampness or mold in their bedroom more than one year prior to the study, vitamin C increased the FEV1 level by only 21% (95% CI: 18-25%). CONCLUSIONS:We found strong evidence that the effect of vitamin C on asthmatic children is heterogeneous. Further research is needed to confirm our findings and identify the groups of children who would receive the greatest benefit from vitamin C supplementation.

SUBMITTER: Hemila H

PROVIDER: S-EPMC3339402 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.

Hemilä Harri H Al-Biltagi Mohammed M Baset Ahmed A AA

Clinical and translational allergy 20110825 1

<h4>Background</h4>We previously found a significant benefit of vitamin C supplementation in asthmatic children.<h4>Purpose</h4>To test whether the effect of vitamin C on asthma is heterogeneous over the participant population.<h4>Methods</h4>Egyptian asthmatic children between 7 and 10 years of age (n = 60) were included in the cross-over trial. They were administered 0.2 grams per day of vitamin C and placebo for separate 6-week periods. The variation in the vitamin C effect on two clinically ...[more]

PMID: 22409829

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Project description:Background An increasing number of studies have suggested that vitamin D can be used to treat childhood asthma, but its clinical effects are still unclear. We conducted this meta-analysis to examine the latest estimates of the effectiveness and safety of using vitamin D to treat childhood asthma. Methods The PubMed, The Cochrane Library, ScienceDirect, Embase, Scopus, Ovid MEDLINE, Web of Science, and Google Scholar databases were searched for randomized controlled trials (RCTs) describing vitamin D supplementation interventions for asthmatic children. Asthma exacerbation, vitamin D levels, the predicted percentage of forced expiratory volume in the first second (FEV1%) and adverse effects (AEs) were analyzed as the main outcome measures. Results After screening, eight RCTs with 738 children were included. Compared with placebos, vitamin D supplementation had a stronger effect on serum vitamin D levels [mean difference (MD) = 13.51 (4.24, 22.79), p = 0.004]. The pooled results indicated that no significant changes were found between the groups in asthma control, as measured by adopting the following indicators: asthma exacerbation [risk ratio (RR) = 0.92 (0.68, 1.25), p = 0.60]; Childhood Asthma Control Test (CACT) scores [MD = 0.15 (−0.43, 0.74), p = 0.61]; hospitalizations for asthma exacerbation [RR = 1.20 (0.48, 2.96), p = 0.70]; acute care visits [RR = 1.13 (0.77, 1.65), p = 0.63]; steroid use [RR = 1.03 (0.41, 2.57), p = 0.95]; and fractional exhaled nitric oxide (FeNO) [MD =-3.95 (−22.87, 14.97), p = 0.68]. However, vitamin D supplementation might reduce the FEV1% [MD = −4.77 (−9.35, −0.19), p = 0.04] and the percentage of predicted forced vital capacity (FVC%) [MD =-5.01 (−9.99, −0.02), p = 0.05] in patients. Subgroup analysis revealed no difference in AEs between the two groups. Conclusions Vitamin D supplementation significantly increased patients' serum vitamin D levels, but it had no benefit for asthma control. However, vitamin D supplementation might reduce patients' lung function. It is essential to systemically search for more large-scale, rigorous, and well-designed RCTs to fully confirm these conclusions. Systematic Review Registration https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021288838, PROSPERO CRD42021288838.

Dataset Information

Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.

Publications

Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.

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